Valve device for pneumatic hoists.



No. 675,528. Patented lune 4, |90l. H. A. RUTHEHFORD.

VALVE DEVICE FOBPNEUMATIC HOISTS.

(Application led Oct. 11, 1900.)

(No Modal.)

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Uivrrnn STATES PATENT Ormes.

ROBERT A. RUTHERFORD, OE PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO TIIE PEDRIOK d: AYER COMPANY, OF SAME PLACE.

VALVE DEVICE FOR PNEUMATIC HOISTS.

SPEGIFICA'EION forming part of Letters Patent No. 675,528, dated June 4, 1901.

Application filed October 11,1900. Serial No. 321685. (No model.)

To f/,Zfl zn/ mnt 'it may! concern: plan View of the auxiliary valve, and Fig. 3 5o Be it known that I, ROBERT A. RUTHER- a central plan view of the casing of the main FORD, a citizen of the United States, residing valve device. at No. 708 Martin street, Philadelphia, in the A represents the cylinder, within which a county of Philadelphia and State of Pennsylhoisting-piston is aliixed to the piston-rod l) Vania, have invented certain new and useful in the usual manuel', the load being connected 55 Improvements in Valve Devices for Pneuat the lower end ot the piston-rod.

maticlfloistsf which thefollowingisaspeci- The main valve device that controls the Iication, reference being had therein to the Huid-pressure supply that operates the hoist 1o accompanying drawings. is contained in the casing 0 and communi- This invention relates to an improved valve cates with the cylinder A through the orifice 6o device appliedtoapneumatichoistof thetype R, which is open to the pipe s, leading from referred to in Letters Patent of the United the source ot' the fluid-supply. This main States No. GGAS, dated April 3, 1000, wherevalve device forms no part of the present inin in operation pressure is admitted to both vention, it being referred to and claimed in sides of the hoisting-piston to establish an another application for a patent tiled by me equilibrium of pressure and exhausted alter- August 9, 1900, Serial No. 26,334, the pipes s nately from the upper side ofthe piston to the and o, valves D and P within the respective atmosphere to elevate the piston and lift the chambers II and K, the springs h and m,

zo load and from the lower side of the piston to valve-rods r and n, the communicating pasits upper side to depress the piston and lower sage N, the passage D2 to the atmosphere, 7o the load. In the patent referred to a reliefand the operating-lever L2, vibrating upon valve independent of the operating-valve is the pivot .2', being counterparts of the deadapted to automatically open the communivice referred to in said application. In said z5 cation between the upper side of the piston application the mechanism for automaticand the atmosphere to reduce the pressure ally maintaining the suspended load in its above the piston when the piston incidentally elevated position connects with the operatsettles or moves downward and close when ing-lever L2 and acts only to relieve the pressaid pressure is reduced to a degree to check sure from the upper side of the piston when 3o said downward movement and permit the the piston settles downwardly with the suspiston to return to its normal suspended popended load, the effect being to arrest and 8o sition. restore the piston and load to the normal In the present invention a valve is adapted suspended position. In the present instance to communicate with either side ofthe piston a separate and independent valve device is 35 and automatically govern either an upward employed, adapted to automatically distribor downward similar movement thereof. nte the pressure upon either side ot the pis- The present invention consists in a sepaton to check either its upward or downward rate and independent valve device communimovement and maintain the load in its decating with the supply-pipes leading to the sired suspended position. This separate and 4o opposite sides of the piston and with the atindependent valve is shown at A and is mosphere operated by devices controlled by constructed with passages J' Jg, that register 9o a movement of the piston in either an upwith the ports I I2, leading to the pipes sand ward or downward direction and adapted to fu, which communicate with the respective automatically change the pressure upon the sides of the piston in the main cylinder A and opposite sides of the piston, so as to maintain with the port c, that opens to the atmosphere.

and hold it in a given position. This valve A2 is oscillated by means of the 95 In the accompanying drawings, Figure l is lever B, connecting-rod C2, and vibrating lea side elevation, partly in section, showing ver E2, the latter being pivoted to a rigid post all the essential parts ot' the hoist; Fig. 2, a F depending from the main cylinder, and

coupled ate, witha friction-'clutch E placed upon the piston-rod b. The clutch E is similar to that shown in my former application and its degree of friction regulated to operate the valve A2 and also allow the piston-rod to move therethrough after the limited movement of the Valve A2 is eiiected.

The main valve device is operated through the rocking lever L2 directly by hand or by chains or rods connected at each extremity, the valve rods rr' and n being alternately forced upwardly, when the lever L2 is accordingly rocked to bring the end of the respective rods in Contact therewith.

In operation to raise the load the valve P is first lifted, which opens communication from the upper side of the piston to the atmosphere through the pipe 'u and escape-passage D2, the pressure-supply through the pipe s being in open communication with the lower side of the piston through the opening R. W hen the load has reached the desired elevation, the movement of the lever L2 is reversed, which opens the valve D, and simultaneously the valve Pis seated by the spring fm, which closes the communication with the atmosphere, and the pressure-supply is admitted to the upper side of the piston from the chamber-H through the passage N and pipe "v, whereby an equilibrium of pressure *A is established on both sides ofthe piston.

The lever L2 is now brought to its horizont-al position, which permits the valves D and P toi Seat, and the piston is thereby heid in its elevated position by the confined pressure on" vitsr opposite sides. Vhen it is desired to lower the piston and its load, the lever L2 is rocked to open the valve D, which opens communication between the pressuresupply and both sides of the piston, which is thereby forced downwardly by the supply-pressure acting upon the greater supericial area of its upper side in amount equal to the area occupied by the piston-rod upon its lower side, the pressure beneath the piston being transferred in the movement to its upper side. During the suspension of the load the natural tendency of the piston is to lower or settle downwardly, due principally to leakage, and this condition has been met and remedied by devices referred to in the Letters Patent and in the specification heretofore mentioned.

In the present invention the device for correcting this incidental downward movement is also adapted to apply to a corresponding upward movement of the piston.

In the position shown in Fig. l of the drawings the valve A2 is open to the upper side of the piston through the port I2 and pipe o and closed to the supply-pipe s and lower side of the piston and the port c to the atmosphere. A downward movement of the piston will, through the connecting mechanism with the piston-rod, turn the valve so that the port J2 will register with the port I2, leading to the pipe o, and the port c, leading to the atmosphere. This will relieve the pressure from above the piston sufficient to arrest its movement and cause it to return to its normal suspended position, the return movement also returning the valve A2 to its former position, and to close the escape-port c. movement of the piston will by the same instrumentalities operate4 the valve to open communication between the supply-pipe s and pipe o, leading to the upper side 0f the piston, respectively, through the port I',valve port J2, and port I2, thus transferring the supply-pressure to the upper side of the piston, and thereby 'checking its upward movement and returning it toits normal suspended position, the balancing pressure acting on its preponderating area, the movement also causing the valve A2 to return to its startingpoint, thus closing the communication with the supply-pipe S and checking the further downward movement.

Having thus fullydescribed myinvention, what I claim, and desire to secure by Letters Patent, is-

In a pneumatic hoist comprising a cylinder,

.piston and piston-rod and valve device whereby in operation the motive fluid may be admitted to establish an equilibrium of pressure upon both sides of the piston, an auxiliary valve device adapted to communicate with the supply-pipes leading to the respective sides of the piston and to the atmosphere, and means for automatically operating said valve device, so that the pressure is adjusted to check a movement of the piston from its suspended position in either an upward or downward direction, as set forth.

In testimony whereof I aflix my signature in presence of two witnesses.

ROBERT A. RUTHERFORD. Witnesses:

J. W. RITTER, JNO. A. CARLISLE.

An upward IOO 

